Classical peptide structures are very sensitive to proteases in vivo and degrade quickly after entering organisms. The sensitivity of the active peptide to protease can be reduced by modifying the active peptide with a long-chain compound, thereby effectively prolonging the half-life of the active peptide in the organism, and improving the possibility of using the active peptide as clinical drug.
Although there are many cases where the active peptides are successfully modified with long-chain compounds, the preparation of long-chain compound is rarely reported in the literature. A traditional preparation method uses an orthogonal protection strategy, in which protecting groups on the branched chain are removed after the synthesis of the main chain is completed. Such method will cause a reduction of solubility of the intermediate, thus a solvent with high boiling point is required in the reaction. Moreover, the post-processing is troublesome, so the method is adverse for large-scale production.